Presser foot mechanism



June 1943- B. T.- LEVEQUE PRESSER FOOT MECHANISM Original Filed April 19, 1959 2 Sheets-Sheet l June 8, 1943. B. T. LEVEQUE PRESSER FOOT MECHANISM Original Filed April 19, 1959 2 Sheets-Sheet '2 JDDDDDDDDDDDDDD I Patented June 8, 1943 PRESSER FOOT MECHANISM Bernard '1. Leveque, Wenham, Mass., assignor to United Shoe Machinery Corporation, Flemington, N. 3., a corporation of New Jersey Original application April 19, 1989, Serial No. 268,708. Divided and this application September 29, 1941, Serial No. 412,748

5 Claims.

The present invention relates to presser foot mechanism for sewing machines and is herein disclosed as embodied in a shoe sewing machine of the so-called McKay type illustrated and described in U. S. Letters Patent of the present inventor No. 2,283,073, granted May 12, 1942, on an application Serial No. 268,708, filed April 19, 1939, of which the present application is a division,

The object of the invention is to provide an improved presser foot actuating mechanism particularly applicable to machines of the type disclosed in applicants patent above referred to, but which also may be used to advantage in other types of sewing machines.

With this object in view, the several features of the invention consist in the novel constructions and arrangements of parts hereinafter described and claimed, the advantages of which will be obvious to those skilled in the art.

In the drawings illustrating the invention in its preferred form, Fig. 1 is a view in front elevation of the head of the sewing machine, with the front cover of the frame removed; Fig. 2 is a partially sectional view, with the frame broken away, of the presser foot actuating mechanism; Fig. 3 is a view in section of the presser foot clutch taken along the line 3-3 of Fig. 2; Fig. 4 is a sectional view of the presser foot clutch taken along the line 4-5 of Fig. 3; Fig. 5 is a sectional View of the presser foot clutch taken along the line 5-5 of Fig, 3; and Fig. 6 is a detail view of a portion of the presser foot unlocking mechanism, as viewed from the front of the machine.

The sewing machine illustrated in the drawings is of the McKay type arranged with a straight hook needle, a rotatable shoe supporting horn, the tip of which is indicated by the dot-dash lines I, and other stitch devices for sewing a lockstitch seam. So far as the general manner of sewing is concerned, the machine is much the same as the machine illustrated in the applicants prior Patent No. 1,885,927, dated November l, 1932. In the operation of this machine, each stitch is formed by interlocking a loop of needle thread with a locking thread during one cycle of stitch forming operations and the stitch thus formed is set during a succeeding cycle of operations.

In the machine illustrated, the stitch forming and work feeding devices include, in addition to the straight needle indicated at 2 (see Fig. 1), a straight work penetrating and feeding awl 4 at the side of the work with the needle, a loop taker or shuttle 6, a loop spreader 8, a presser foot I0 and a take-up, a needle thread tension and lock and a rotary needle looper or whirl, not shown in the drawings of the present application, but fully illustrated and described in inventors Patent No. 2,283,073. r

The presser foot, as best shown at Iii-in Fig. 1, is secured to the lower end of a vertical bar I2 slidingly supported in the head frame of the machine and held yieldingly in lowered position by a relatively light spring I4 coiled about the upper end of the bar between a shoulder on the bar and an adjustable threaded sleeve l6 forming an upper bearing for the bar. The presser foot is actuated in the usual Way to release the work before each feeding movement of the awl takes place, and to hold the work in place both while the needle and a'wl are being retracted from the work and while each stitch is being set by the shuttle.

To avoid the use of heavy spring pressure on the presser foot, as in previous machines, while permitting the machine to be operated at high speeds, the presser foot is actuated positively in the present machine through cam actuated mechanism towards the work and just before the presser foot reaches a work clamping position, the cam actuated mechanism is disconnected from the presser foot so that the presser foot may take a position determined by the thickness of the work, the actuating spring not being required to move the presser foot, but merely holding it in position when stopped by the work. A spring of proper strength to move the presser foot from raised position into engagement with the work with sufiicient rapidity when the machine is operating at high speed ordinarily would cause the presser foot to strike the work with such force as to produce undesirable indentations. By positively actuating the presser foot in the manner outlined, a lighter actuating spring may be used so that indentation of the work from this cause is avoided.

The mechanism for actuating the presser foot comprises an oscillating clutch, the driven member of which is connected to the presser foot bar l2 by means of a link l8 connected at its lower end to a stud 200m a block 22 secured to the presser foot bar and connected at its upper end to an arm projecting from the driven member 24 of the clutch. The driven member 24 is in the form of a drum and is rotatably mounted on the horizontal shaft 26 .at the for- Ward part of the sewing head frame. The driving member 28 of the clutch is rotatably mounted on the shaft 26 at one side of the driven member 24 and extends within the overhanging rim of the driven member, as best shown in Fig. 4. To actuate the driving member 28, it is positively connected by interlocking projections and notches to the hub of an arm 36 also rotatably mounted on the shaft 26 and connected by a link 32 (see Fig, 2), to a cam actuated lever 34 mounted to oscillate on a stud 35 secured in the machine frame. Oscillation of the lever 34 oscillates the driving member of the clutch to impart upward and downward movements to the presser foot bar, as hereinafter described, the extent of which movements can be varied by adjusting the pivotal connections 38 of the link 32 with the lever 34 along a curved slot in the lever.

Means are provided for locking the driven and driving members 24, 28 of the clutch together and for unlocking them during each stitch forming cycle, the presser foot bar being positively actuated in both directions so long as the clutch members are locked, and being free from the influence of the clutch as soon as the members are unlocked. The clutch members are locked during the greater part of each stitching cycle and are unlocked just before the presser foot clamps the work.

The means for locking and unlocking the members 24, 28 of the clutch comprise a series of tapered rolls 49 located between the members, as best shown in Figs. 4 and 5, and fitting against a correspondingly tapered surface on the inner side of the overhanging rim of the driven member 24. The rolls are held in recesses in the periphery of the driving member 28, which recesses are pro-- vided with tapered surfaces extending axially in contact with the rolls and act to move the rolls bodily with the driving member in each direction as the driving member is oscillated. Alternate recesses in the driving clutch member have surfaces engaging the rolls which slope outwardly away from the axis of rotation in opposite directions, as clearly shown in Fig. 5, which cause certain of the rolls to lock the clutch members together when the driving member is rotated in one direction and cause the other rolls to lock the members together when the driving member is rotated in the other direction, the action of each set of rolls being similar to that of the well-known Horton clutch. The wedging surfaces of the clutch members are so disposed that the tapered rolls, when moved axially to the right, as viewed in Fig. 4, become wedged between the surfaces and lock the clutch members together so as to prevent relative movement in either direction. When the rolls are withdrawn axially from the tapered spaces between the clutch members, the clutch members are disconnected.

The tapered rolls 40 are held in an axially movable retaining cage 42 surrounding the shaft 26 between a collar portion of the cage and a plurality of curved fingers at the opposite end of the cage. To press the tapered rolls an equally into engagement with the clutch members, when the cage is moved axially, each roll is provided with a central recess within which is held a compression spring 44 supported by the collar portion of the retaining cage.

To disconnect the clutch members 24 and 28 at the proper time in each stitching cycle, so that the presser foot may yieldingly engage the work, the cage 32 is actuated along the shaft 2% in a direction. to withdraw the tapered rolls 46 from between the clutch members. To so actuate the cage, an unlocking bar 46 is mounted in a horizontal guideway of the head frame and is provided with a forked plate 48 fitting between a flange of the cage and a collar secured to the hub of the cage. Referring to Figs. 1 and 6, the lower surface of the unlocking bar is formed with rack teeth, engaging a segment 50 connected to one end of a rock shaft 52 having at its other end an arm 54 provided with a cam roll 55. At the right end of the unlocking bar 46 is an axial bore arranged to receive a spring 58, the outer end of which engages a cover plate secured to the side wall of the head frame. The spring 53 tends to force the bar 46 towards the left, causing the cam follower 56 to engage the outer surface of a cam 58 on the main sewing shaft.

The cam for actuating the presser foot lifting lever 34 is so cut that the presser foot is raised to release the work as the beak of the shuttle enters the needle loop, thus permitting the needle thread extending through the needle opening in the horn to move more freely between the undersurface of the work and the tip of the horn as the needle loop passes over the shuttle. Just as the previous stitch is set, and while the work is still released, the presser foot is lowered to hold the work lightly against the tip of the horn, after which the presser foot clutch is unlocked to allow the position of the presser foot to take a proper clamping position on the work.

The nature and scope of the present invention having been indicated and a construction embodying the several features of the invention having been specifically described, what is claimed is:

1. A sewing machine having, in combination with the stitch forming devices, a work support, a presser foot, and means for pressing the presser foot yieldingly against the work, means for actuating the presser foot comprising a driving clutch member, a driven clutch member, connections from the driven clutch member to the presser foot, means for actuating the driving clutch member first in one direction to raise the presser foot from the work and in the other direction to move the presser foot positively towards the work, and means for disconnecting the driving and driven clutch members in each stitch forming cycle just before the presser foot clamps the work.

2. A sewing machine having, in combination with the stitch forming devices, a work support, a presser foot, and means for pressing the presser foot yieldingly against the work, means for actuating the presser foot comprising a driving clutch member, a driven clutch member, connections from the driven clutch member to the presser foot, means for actuating the driving clutch member first in one direction to raise the presser foot from work clamping position and in the other direction to move the presser foot positively towards clamping position, and means for disconnecting the driving and driven clutch members in each stitching cycle before the presser foot reaches clamping position and for reconnecting the driving and driven clutch members after the presser foot yieldingly presses the work.

3. A sewing machine having, in combination with the stitch forming devices, a work support, a presser foot, means for pressing the presser foot yieldingly against the work, driving and driven clutch members having wedging surfaces,

tapered rolls arranged to be wedged between said surfaces, connections from the driven clutch member to the presser foot, and means for moving the rolls axially to connect and disconnect the driving and driven clutch members.

4. A sewing machine having, in combination with the stitch forming devices, a work support, a presser foot, means for pressing the presser foot yieldingly against the work, rotary driving and driven clutch members having opposed wedging surfaces, connections from the driven clutch member to the presser foot, and means for actuating the driving clutch member to raise and lower the presser foot from and towards the work, rolls engaging the wedging surfaces of the clutch members to lock the members together, and means for releasing the rolls in each stitch forming cycle from engagement with said surfaces to permit the presser foot to yieldingly engage the Work.

5. A sewing machine having, in combination with the stitch forming devices, a work support, a presser foot, means for pressing the presser foot yieldingly against the work, rotary driving and driven clutch members having opposed wedging surfaces, connections from the driven clutch member to the presser foot, and means for actuating the driving clutch member to raise and lower the presser foot from and towards the work, tapered rolls engaging the wedging surfaces of the clutch members to lock the members together, spring means for pressing the rolls endwise in a direction at right angles to the rotary movement of the clutch members into the space between the clutch members to lock the members together, and means for pressing the rolls in each stitch forming cycle endwise in the opposite direction to permit the presser foot to yieldingly engage the work.

BERNARD T. LEVEQUE. 

